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...I always thought they were for height, not width though. Interesting!
Well, they are for height in a sense. If they get knocked off, your truck was too high for what you tried to drive under.
Seriously though, and technically, only the outer two cab roof lights are clearance lights. The middle three are "identification lights" as defined by USDOT.
The outer two and the side marker lights identify the widest parts of a vehicle, and the middle three tell other drivers the vehicle is wider than 8' 6". In addition, three red identification lights and two red clearance lights are required on the rear of motor vehicles (excepting truck tractors) and trailers wider than 8' 6".
Well, they are for height in a sense. If they get knocked off, your truck was too high for what you tried to drive under.
Seriously though, and technically, only the outer two cab roof lights are clearance lights. The middle three are "identification lights" as defined by USDOT.
The outer two and the side marker lights identify the widest parts of a vehicle, and the middle three tell other drivers the vehicle is wider than 8' 6". In addition, three red identification lights and two red clearance lights are required on the rear of motor vehicles (excepting truck tractors) and trailers wider than 8' 6".
Joe
I've ordered them on my truck because I'll need them and I just like them.
I do have to kinda chuckle about it though. Most of the people on a truck forum don't know exactly what they're for, let alone the general public, so you have to wonder how effective they really are at doing what they're intended to do!
I saw a DRW pass by me last night and while I was looking at the clearance lights, the fenders still stick out on either side obviously wider than the lights on the roof. I did see the light on the fender as well. Like this pic.
With them being called roof clearance lights I thought how would you know if you have cleared the height requirement until the lights have been knocked off your truck...lol
It's a lot cheaper to replace a light or two rather than pay for body work. There's a truck at work that has cab light on the front AND back. In certain situations it could keep your from a hefty bill.
I measured the height of the tallest part of my roof (with a near empty fuel tank) and then placed a piece of electrical tape at that height (+1") on my radio antenna for a visual check entering parking facilities, fast food joints w/ awnings, garages etc.
I measured the height of the tallest part of my roof (with a near empty fuel tank) and then placed a piece of electrical tape at that height (+1") on my radio antenna for a visual check entering parking facilities, fast food joints w/ awnings, garages etc.
It has nothing to do with commercial vehicles. The "precise" reason is very simple. If you are wider than 8'6", they are required. If you are not, they are an accessory.
DRW's also have the marker lights on the fenders. When I was driving commercially I had an issue with that... got held at a weigh station for 2 hours for the light, logging issue, and a "brake" issue. I was Out of Service for at least a day after that one - mostly because of the logging issue and another driver of ours a short time before. Oh well. Its a story to tell now The DOT likes to stack everything up, whatever they can find, and I wonder sometimes if some of it is what they "create".... What are you going to do? Sit and argue with them?
I measured the height of the tallest part of my roof (with a near empty fuel tank) and then placed a piece of electrical tape at that height (+1") on my radio antenna for a visual check entering parking facilities, fast food joints w/ awnings, garages etc.
They're required on vehicles over 80 inches wide, not including mirrors. Standard on dually, optional on SRW. They did a really nice job of incorporating them into the F150 Raptor (due to the wide fender flares).